1. Technical Field
This disclosure relates to power control systems and, more particularly, to dynamically-compensated controllers used in DC power supplies.
2. Description of Related Art
DC power supplies may regulate their output by varying a switching signal that is used to controllably deliver energy to their output based on a comparison of the output and a target value.
Feedback circuits may be used to generate the switching signal. These feedback circuits may be optimized to maximize the speed at which they compensate for changes in the load and/or source supply, without instability.
The characteristics of the components which are used in the feedback circuit and elsewhere can vary due to variations in manufacturing processes, temperature changes, and/or aging. These component variations, in turn, can diminish the performance of the feedback circuit, thus reducing the speed at which it compensates for changes in the load and/or source supply and/or its stability.
One approach to addressing this problem is to design the feedback circuit to provide adequate performance, notwithstanding anticipated changes in component value. Such designs, however, often resolve in performance compromises and/or a requirement for an output filtering capacitance that is larger than what would otherwise be needed. It may also be difficult to anticipate the nature of load transients and, as a result, to provide a design that adequately handles them.
Another approach to addressing this problem is to dynamically compensate the feedback circuit for these changes. During operation of the feedback circuit, a perturbation signal of known characteristics may be injected into the feedback loop, causing a corresponding perturbation in the output of the DC supply. The perturbation in the output may be compared to the injected perturbation. Based on this comparison, one or more performance characteristics of the feedback circuit may be determined. Performance characteristics of the feedback circuit may then be dynamically optimized as needed.
Accurately measuring the perturbation on the output which is caused by the injected perturbation, however, can be challenging. For example, it may be difficult to distinguish the output perturbation from noise on the output of the supply, such as noise caused by switching ripple and/or load transients. The DC output of the power supply may also be very substantial in comparison to the output perturbation. This may make it difficult to accurately measure characteristics of the output perturbation, without very sensitive circuitry, such as a high resolution analog-to-digital converter. Such devices can be expensive and/or require significant chip real estate.